Logo Search packages:      
Sourcecode: mathpiper version File versions  Download package

And.java

/* {{{ License.
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */ //}}}

// :indentSize=4:lineSeparator=\n:noTabs=false:tabSize=4:folding=explicit:collapseFolds=0:
package org.mathpiper.builtin.functions.core;

import org.mathpiper.builtin.BuiltinFunction;
import org.mathpiper.lisp.Environment;
import org.mathpiper.lisp.cons.ConsTraverser;
import org.mathpiper.lisp.cons.ConsPointer;
import org.mathpiper.lisp.Utility;
import org.mathpiper.lisp.cons.SublistCons;

/**
 *
 *  
 */
public class And extends BuiltinFunction
{

    public void evaluate(Environment aEnvironment, int aStackTop) throws Exception
    {
        ConsPointer nogos = new ConsPointer();
        int nrnogos = 0;
        ConsPointer evaluated = new ConsPointer();

        ConsTraverser consTraverser = new ConsTraverser((ConsPointer) getArgumentPointer(aEnvironment, aStackTop, 1).car());
        consTraverser.goNext();
        while (consTraverser.getCons() != null)
        {
            aEnvironment.iLispExpressionEvaluator.evaluate(aEnvironment, evaluated, consTraverser.getPointer());
            if (Utility.isFalse(aEnvironment, evaluated))
            {
                Utility.putFalseInPointer(aEnvironment, getTopOfStackPointer(aEnvironment, aStackTop));
                return;
            } else if (!Utility.isTrue(aEnvironment, evaluated))
            {
                ConsPointer ptr = new ConsPointer();
                nrnogos++;
                ptr.setCons(evaluated.getCons().copy( aEnvironment, false));
                ptr.cdr().setCons(nogos.getCons());
                nogos.setCons(ptr.getCons());
            }

            consTraverser.goNext();
        }

        if (nogos.getCons() != null)
        {
            if (nrnogos == 1)
            {
                getTopOfStackPointer(aEnvironment, aStackTop).setCons(nogos.getCons());
            } else
            {
                ConsPointer ptr = new ConsPointer();

                Utility.reverseList(ptr, nogos);
                nogos.setCons(ptr.getCons());

                ptr.setCons(getArgumentPointer(aEnvironment, aStackTop, 0).getCons().copy( aEnvironment, false));
                ptr.cdr().setCons(nogos.getCons());
                nogos.setCons(ptr.getCons());
                getTopOfStackPointer(aEnvironment, aStackTop).setCons(SublistCons.getInstance(aEnvironment,nogos.getCons()));

            //aEnvironment.CurrentPrinter().Print(getTopOfStackPointer(aEnvironment, aStackTop), *aEnvironment.CurrentOutput());
            }
        } else
        {
            Utility.putTrueInPointer(aEnvironment, getTopOfStackPointer(aEnvironment, aStackTop));
        }
    }
}



/*
%mathpiper_docs,name="And",categories="User Functions;Predicates;Built In"
*CMD And --- logical conjunction
*CORE
*CALL
      a1 And a2
Precedence:
*EVAL OpPrecedence("And")

      And(a1, a2, a3, ..., aN)

*PARMS

{a}1, ..., {a}N -- boolean values (may evaluate to {True} or {False})

*DESC

This function returns {True} if all arguments are true. The
{And} operation is "lazy", i.e. it returns {False} as soon as a {False} argument
is found (from left to right).  This is faster, but also means that none of the
arguments should cause side effects when they are evaluated.
 If an argument other than {True} or
{False} is encountered a new {And} expression is returned with all
arguments that didn't evaluate to {True} or {False} yet.
{And(...)} and {Or(...)} do also exist, defined in the script
library. You can redefine them as infix operators yourself, so you have the
choice of precedence. In the standard scripts they are in fact declared as
infix operators, so you can write {expr1 And expr}.

*E.G.

      In> True And False
      Out> False;
      In> And(True,True)
      Out> True;
      In> False And a
      Out> False;
      In> True And a
      Out> And(a);
      In> And(True,a,True,b)
      Out> b And a;

*SEE Or, Not
%/mathpiper_docs
*/

Generated by  Doxygen 1.6.0   Back to index